BEIJING - RESCUERS searched on Sunday for 17 workers missing after a subway tunnel they were building in eastern China caved in, killing at least three people, the state news agency said.

A 250-foot (75-metre)-wide section of road over the construction site collapsed in the eastern city of Hangzhou on Saturday, trapping workers and creating a huge crater into which at least 11 vehicles plunged.

Poor construction quality is a chronic problem in China, and is often blamed on bad planning, shoddy work or theft of materials.

The official Xinhua News Agency said rescuers were still pumping out water that had seeped into the tunnel from a nearby river and stood at 10-foot (3-metre) -deep.

Those missing were believed to be construction workers, Xinhua said.

'There is a slim chance for the survival of trapped workers because of heavy flooding in the crater,' Xinhua quoted Wang Guangrong, spokesman for the rescue team, as saying on Sunday. Mr Wang said 19 injured people were sent to a hospital for treatment.

Phone calls to the local and provincial work safety bureaus were not answered Sunday.

Mr Wang told Xinhua that rescuers pulled out the vehicles that had plunged into the crater and that all the drivers and passengers were safe. Three houses near the cave-in have been evacuated, Wang said.

Xinhua said authorities were not ruling out the possibility of more collapses along the tunnel's route, and construction workers were dispatched to install supports along the remaining sections to reinforce the tunnel. The provincial governor ordered a suspension of subway construction, the report said.

China Railway Construction Group Co. Ltd., the company building the tunnel, has launched a safety examination of the project, the report said.

The 43-mile (68.8-kilometre) subway project, begun in March last year, is being built at a cost of US$5.1 billion (S$7.75 million) and is due to be completed in 2011, Xinhua said.

The accident is the latest in China amid a frenzy of subway construction. More than a dozen cities received approval to build new subway systems in recent years, joining those already in use in major cities such as Beijing and Shanghai.

Last year, four construction workers were killed when a subway line being built for this year's Beijing Olympics caved in. Two months later, another accident at a subway construction site in the eastern city of Nanjing killed two workers. -- AP